Department of Neurology, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan.
Department of Neurology, Tokushima University Graduate School of Biomedical Sciences, Tokushima, Japan.
Muscle Nerve. 2023 Sep;68(3):257-263. doi: 10.1002/mus.27829. Epub 2023 Apr 22.
INTRODUCTION/AIMS: Reliable neurophysiological markers in amyotrophic lateral sclerosis (ALS) are of great interest. The compound muscle action potential (CMAP) amplitude has been a conventional marker, although it is greatly influenced by the electrode position. We propose the far-field potential of the CMAP (FFP-CMAP) as a new neurophysiological marker in ALS.
Patients with ALS and age-matched healthy controls were enrolled. We used a proximal reference (pref) in addition to the conventional distal reference (dref). Routine CMAP was recorded from the belly-dref lead and FFP-CMAP from the dref-pref lead for the ulnar and tibial nerves. Multiple point stimulation motor unit number estimation (MUNE) was also examined in the ulnar nerve. Inter-rater reproducibility was evaluated by two examiners, and some patients were followed up every 3 mo for 1 y.
We tested 17 patients with ALS and 10 controls. The amplitudes of routine CMAP and FFP-CMAP in the ulnar and tibial nerves, and hypothenar MUNE value in the ulnar nerve were significantly decreased in ALS compared to controls. Ulnar FFP-CMAP achieved the highest inter-rater intraclass correlation coefficient (ICC) value (0.942) when compared with routine CMAP (0.880) and MUNE (0.839). The tibial FFP-CMAP had a higher ICC value (0.986) than the routine CMAP (0.697). In this way, the FFP-CMAP showed high inter-rater reproducibility because its shape was not much influenced by the electrode position. During 1-y follow-up, decline of CMAP, FFP, and MUNE showed significant correlations with the Amyotrophic Lateral Sclerosis Functional Rating Scale - Revised (ALSFRS-R).
The FFP-CMAP shows promise as a reliable marker for ALS.
简介/目的：肌电图（EMG）在肌萎缩侧索硬化症（ALS）中是一个很有意义的指标。复合肌肉动作电位（CMAP）的波幅一直是一个常规指标，尽管它受电极位置的影响很大。我们提出 CMAP 的远场电位（FFP-CMAP）作为 ALS 的一个新的神经生理学指标。
我们纳入了 ALS 患者和年龄匹配的健康对照组。我们除了常规的远端参考（dref）外，还使用了近端参考（pref）。常规 CMAP 是从腹部-dref 导联记录的，FFP-CMAP 是从 dref-pref 导联记录的，用于尺神经和胫神经。还对尺神经进行了多点刺激运动单位数估计（MUNE）。两名检查者评估了组内再现性，一些患者在 1 年内每 3 个月随访一次。
我们共检测了 17 名 ALS 患者和 10 名对照组。与对照组相比，ALS 患者的尺神经和胫神经常规 CMAP 和 FFP-CMAP 波幅，以及尺神经小鱼际 MUNE 值明显降低。与常规 CMAP（0.880）和 MUNE（0.839）相比，尺神经 FFP-CMAP 的组内再现性最高的组内相关系数（ICC）值（0.942）。胫神经 FFP-CMAP 的 ICC 值（0.986）高于常规 CMAP（0.697）。以这种方式，FFP-CMAP 显示出较高的组内再现性，因为其形状不受电极位置的影响很大。在 1 年的随访中，CMAP、FFP 和 MUNE 的下降与肌萎缩侧索硬化功能评定量表修订版（ALSFRS-R）有显著相关性。
FFP-CMAP 有望成为 ALS 的可靠标志物。
